Electric discharge tube



May 28, 19.35. .1. w. RYDE A ELECTRIC DISCHARGE TUBE Filed May 29, 1934 /r3 wsl, {2251,1 5 V Patented May28,193 2,002,837 I ELECTRIC DISCHARGE TlJBE John Walter Ryde, London, England, as signor to The General Electric Company Limited, London, England Application May 29, 1934, Serial No. 728,101

. In Great Britain April 4, 1933 3 Claims. (Cl, 176-122) This invention relates to electric discharge tubes In Figure 2 the end wall of the tube is composed of the type in which all parts of the tube have to of two parts, one being narrower than the rebe maintained above some temperature greatly mainder of the tube. The sleeve now fits closely exceeding atmospheric, in order that the vapour the narrow part as in Figure l, but projects into 5 pressure of some substance contained in it may the wider portion and is furnished with a collar 5 attain a desired value. 6, extending into the wider portion which fits the In such tubes the portions most likely to fail to connecting .wall closely in the region wherethe attain the requisite temperature are the ends, and change of diameter occurs; for this region is apt especially the ends behind the electrodes. Many to beam of relatively low temperature.

methods of heating the ends have been described; If the discharge is of the constricted type and some of these involve metal sleeves outside the most of it occupies an area of the cross section of tube. The object of the invention is to provide the tube much less than the whole, the modificaan improved method of heating these ends. tion of Figure 1 shown in Figure 3 may be adapted.

According to the invention, an electric discharge Here the end of the sleeve which is open in Figure 5 tube of the type specified comprises a hollow metal 1 has portions 1 turned inwards, so that it lies in body within the tube, not being an electrode of the region of the discharge from which most heat the discharge, fitting the end wall of the tube is to be derived, while the remainder of the body closely over a substantial part of its surface, so fits closely the end wall of the tube. shaped and extending so far into the region be-- It iS Preferable that the metal b y ShOuld X- tween the main electrodes that one part of the tend further into the space between the electrodes 20 body receives heat from the discharge and comthan is shown in the drawing. municates it by conduction to those parts that fit By an obvious modification Figure 4 is reached, closely the end 'wall of the tube whereby the said where there is no sharp distinction between the end wallis heated. portion turned inwards and the remainder, part I It is necessary for. this purpose that some part of the body being a cone tapering towards the 26 of the said metal body should extend into the centre line. This form is appropriate when the space between the electrodes that carry the disonly part of the tube that requires to be heated charge during the operation of the tube. For is the extreme end.) otherwise they will not receive any substantial The exterior surface of the metal body in any 30 amount of heat from the discharge. Thus the of Figures 1, 2, 3 and 4 and in any other ar- 30 metal cases l2, 13 of Figure 1 of British Patent rangements according to the invention is preferspecification "'No 392,509 are not metal bodies ably polished, so that little heat is lost by radiaaccording to the invention, for while they extend tion; its interior surface is preferably blackened into the space between the auxiliary electrodes, so as to absorb radiant heat from the discharge.

36 they do not, extend into the space between the I claim: main electrodes 4, 5. 1. An electric discharge tube comprising an Certain embodiments of the invention will now envelope, a pair of main disch'arge'electrodes arbe described with reference to the accompanying ranged within the envelope, leads passing through drawing, in which Figure 1 shows in section a disthe envelope to the electrodes, a vaporizable sub- 40 charge tube and Figures 2, 3 and 4 show in section stance within the envelope and a hollow metal 40 the end portions-of modified discharge tubes conbody fitting closely the interior of the end wall taining these embodiments. In all figures |-rep-. of the, envelope adjacent to one of the electrodes resents the wall of the'tube, 2 an electrode at this and out of contact with the leads so that it will end, 3 the hollow metal body according to the innot act as an electrode, said body having a part vention, l, l apertures in the end of the metal extending into the region between the electrodes 45 body nearest the end of the tube, through which so as to intercept heat from the discharge, the pass leads 5, 5' to the electrode 2, these leads beheat being conveyed through the metal body and ing out of contact with the metal body 3. the portion closely fitting the end wall to heat In Figure l the end wall of the tube is substanthe latter.

tially the hemi-spherical end of a cylinder. The 2. An electric discharge tube comprising an metal body 3 is then a sleeve the whole of whose envelope, a pair of main discharge electrodes arexterior surface closely fits the interior of the ranged within the envelope, leads passing through hemispherical end wall. It must be so long that it the end walls of the envelope to the elctrodes, a.

reaches a part of the tube adequately heated by vaporizable substance within the envelop and a the discharge. hollow metal body adjac t0 one Of the trodes and fitting closely the interior of the wall through which said leads pass; said body being provided with holes to space it from the leads so that it will not act as an electrode, said body having apart extending into the region between the electrodes so as to intercept heat from the discharge, the heat being conveyed through the metal body and the portion thereof closely fitting the end wall to heat the latter.

3. An electric discharge tube comprising an envelope, a pair of .main discharge electrodes arranged within th envelope, leads passing through the envelope to the electrodes, 9. vaporimble substance within the envelope and a hollow metal -body fitting closelythe interior of the end wall of the envelope adjacent to one 0! the electrodes and out of contact with the leads so that it will not act as an electrode, said body having a part extending into the region between the electrode so as to intercept heat from the discharge, the heat being conveyed through the metal body and the portion closely fitting the end wall to heat the latter, said body being polished on its exterior 10 surface and blackened on its interior surface.

JOHN WALTER RYDE. 

